Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2017

Assets Measured at Fair Value on Recurring Basis

Following are the major categories of assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016, using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3) (in thousands):

March 31, 2017	Level 1		Level 2		Level 3		Total
Cash equivalents	$	96,932	$	—	$	—	$	96,932
Commercial paper		—		39,828		—		39,828
Marketable securities - corporate bonds		—		49,066		—		49,066
	$	96,932	$	88,894	$	—	$	185,826

December 31, 2016	Level 1		Level 2		Level 3		Total
Cash equivalents	$	188,543	$	—	$	—	$	188,543
Commercial paper		—		5,998		—		5,998
Marketable securities - corporate bonds		—		28,984		—		28,984
	$	188,543	$	34,982	$	-	$	223,525

Summary of Short-term Investments

The following tables summarize the Company’s short-term investments (in thousands):

	Maturity	Amortized		Unrealized					Estimated
March 31, 2017	(in years)	cost		Gains		Losses			fair value
Cash equivalents		$	96,932	$	1	$	—		$	96,933
Commercial paper	Less than 1		39,828		—		—			39,828
Marketable securities - corporate bonds	Less than 1		49,066		3		(54	)		49,015
		$	185,826	$	4	$	(54	)	$	185,776
	Maturity	Amortized		Unrealized					Estimated
December 31, 2016	(in years)	cost		Gains		Losses			fair value
Cash equivalents		$	188,543	$	—	$	—		$	188,543
Commercial paper	Less than 1		5,998		—		—			5,998
Marketable securities - corporate bonds	Less than 1		28,984		—		(13	)		28,971
		$	223,525	$	—	$	(13	)	$	223,512